Suture passing is problematic for the arthroscopic surgeon because the braided suture preferred by most arthroscopists cannot be pushed through a cannulated instrument. Braided suture must be pulled into location because applying a push force causes the braid to expand in diameter, thereby wedging in the instrument.
Various solutions have been devised for passing braided suture. The Caspari Suture Punch (Linvatec Corporation, Largo, Fla.) has been a very useful arthroscopic suture-passing instrument. Tissues can be approached head on, grasped and punctured with a cannulated needle, then monofilament suture wheeled through the tissue. A doubled monofilament can be used as a shuttle to pass another braided suture or, alternatively, a Linvatec Suture Shuttle can be wheeled through a slotted Caspari Suture Punch and used to shuttle suture. Surgical Dynamics has a similar device that shuttles a needle from one side of the punch to the other, passing the needle and attached thread through tissue.
The Caspari suturing instrument, described in U.S. Pat. Nos. 4,890,615, 4,923,461 and 4,957,498, includes a hollow needle for penetrating tissue to be sutured within the body while the tissue is clamped between relatively movable jaws, and a suture feed mechanism for feeding suture material through the hollow needle such that the jaws can be opened and the suturing instrument withdrawn from the body pulling the free end segment of the suture material with the instrument. A knot can be tied in the suture material externally of the body and the knot moved back into the body at a position adjacent the tissue.
U.S. Pat. No. 5,254,126 discloses an endoscopic suture punch for use in endosurgical procedures having an elongate frame and a handle mounted to one end of the frame. A pair of opposed jaws having tissue punches is mounted to the other end of the frame. One jaw is rigidly mounted to the frame while the other jaw is movably mounted to the frame, although both jaws can be movably mounted. An actuation handle is mounted to the frame for actuating the jaws. The suture punch has a suture pathway through the frame, the punches and the jaws for receiving the suture. There is a suture drive mechanism mounted to the frame for moving the suture through the suture pathway.
The surgical suturing apparatus described in U.S. Pat. No. 5,454,823 comprises upper and lower jaw elements selectively movable relative to one another between open and closed position. Each jaw element is provided with a respective recess arranged to receive a portion of an elongate incision member or length of surgical thread and securing means is provided arranged to selectively secure the surgical incision member or length of surgical thread in a respective recess. The jaw elements are typically provided at an end of an elongate positioning and operating arm making the device particularly useful for use in laparoscopic surgery.
More recently, U.S. Pat. No. 6,051,006 describes a suture-passing forceps having a first jaw with a mount which supports a needled suture and a second jaw having a passage, which when aligned with the mount, is positioned to receive the needled suture. The second jaw is positioned relative to the mount in a manner which allows delivery of the instrument to a surgical site in a low profile, delivery position (e.g., with the jaws spaced relatively closely). The surgical instrument includes an elongated shaft having a distal region for supporting the jaws. The second jaw is pivotable, with respect to the mount, between the delivery position in which the second jaw is spaced relatively closely to the mount with the passage misaligned with the mount and an open, misaligned position, the second jaw being axially translatable relative to the mount to an open, aligned position in which the passage is aligned with the mount.
A shortcoming of these and other such devices is the lack of room available to open the jaws sufficiently in tight spaces (a clearance issue), difficulty in forcing the tooth through the full thickness of the tissue (the tip gradually dulls and some tissue like the rotator cuff is just too thick) and fairly large diameter cannulas are required for passage.
Other “blitzes” and similar devices also have rather large diameter cannulated needles that pierce the tissue then deploy a loop or other mechanism to transport suture through the tissue. These are cumbersome to use, often requiring skillful rotation and pushing of the device by the surgeon to accomplish the desired result. Additionally, some concern exists with regard to the size of the hole placed in the tissue and the amount of damage requiring repair. This is especially true of the newer “Arthropierce” instrument currently in use.
Common to existing devices is a body capable undergoing elastic deformation during use but which retains a preformed shape when in an unconstrained condition. Of particular usefulness in these devices is Nitinol, a so-called “shape retention” alloy having an extremely high yield point. Nitinol components are formed during manufacture to a desired shape, and will return to this shape when in an unconstrained condition even after undergoing significant deformation. Preformed Nitinol needles and shuttles can be passed through cannulated instruments and will return to their original shapes when in an unconstrained state. This allows shuttle loops to be passed through cannulated instruments without permanent deformation. All Nitinol components are formed to their desired shapes during manufacture.
As an example of an invention utilizing this effect, U.S. Pat. No. 5,607,435 describes a medical instrument including a tubular section having a leading end terminating in a sharp point and a surgical needle exhibiting “superelastic characteristics.” As such, the needle can remain straight as it is inserted through the delivery tube without developing substantial permanent deformation. While in the delivery tube and in this substantially straight condition, the needle is delivered to the suturing site. Once at the suture site, the surgical needle is extended out of the leading end of the delivery tube, returning it to its original curved or bent shape for suturing. A suture thread or wire is operatively disposed in the bore of the tubular section with one end extending out the tip through a slot so as to remain in position to form a suture upon removal of the tubular needle from tissue. A tweezers instrument may then be used to grip and tie the thread into a suture knot.
Similarly, U.S. Pat. No. 5,749,879 discloses a cannulated instrument for use in conjunction with “an elastic needle.” In the preferred embodiment, the needle is of a pseudoelastic shape memory alloy and has an arced shape while the needle's alloy is in a substantially austenitic phase, and the needle may be stressed into a more straight shape in which the needle's alloy enters an at least partially more martensitic phase. When the needle is held entirely within the cannula, the needle is straightened and contains more stress-induced-martensite phase. As the needle is extruded from the distal end portion of the cannula, that portion of the needle which extends beyond the cannula returns toward its original shape by a martensitic-to-austenitic shape memory phase change caused by at least partial relief of the stress-induced-martensite in the needle's alloy. A cannula insert includes a longitudinal bore which may be used to contain a suture attached to the needle. Suitably, the bore may extend longitudinally entirely through the cannula insert, to permit an unlimited length of suture to be pulled therethrough.
Despite these advances, the need remains for a suture punch capable of passing braided suture without the use of a shuttle or similar means. Preferably, such an instrument would be capable of passing suture while not requiring multiple or complex sequential operations or a high level of surgeon skill. It is also preferable that the suture punch pass through a small diameter (i.e., 8 mm or less) cannula, and that the hole created in the tissue for passage of the suture be as small as possible.